Electric switch



Patented July 26, 1938 UNETED STATES PATENT OFFICE Original application November 11., 1933, Serial No. 697,600. Patent No. 2,095,251, dated October 12, 1937.

Divided and this application October 11, 1937, Serial No. 168,388

9 Claims.

This application is a division of application Serial Number 697,600, filed November 11, 1933, for which Letters Patent No. 2,095,251 were issued on October 12, 1937, for Aircraft flight control,

and relates generally to make and break switches for electrical circuits and more particularly to switches of the liquid contact type.

The principal object of this invention is the provision of a new and improved fluid control SWil/Ch.

Another object is the provision of a fluid contact type switch arranged to control an electrical circuit in response to the effect of one or the combination of a plurality of conditions effecting the operation of the switch.

Another object is the provision of new and improved bafiling for controlling the movement of the liquid within the switch.

A further object is the use of a nonconducting liquid in conjunction with a conducting liquid within the switch to quench the arcs created by the making and breaking of the electrical circuits and to prevent oxidation of the conducting liquid.

Other objects and advantages appear in the following description.

In the accompanying drawing wherein a practical embodiment of the principles of this invention are illustrated:

Fig. 1 is a side elevation of the switch comprising this invention.

Fig. 2 is a view similar to Fig. 1 illustrating the combined effect of two conditions collectively affecting the operation of the switch.

Fig. 3 is an enlarged vertical section taken longitudinally through the liquid containing portion of the switch illustrating the arrangement of the baffle members and the liquid contacting members for connecting the electrical circuits to the switch.

Fig. t is a plan View of the longitudinal baflle member shown in Fig. 3.

Figs. 5. 6 and 7 are cross sectional views taken along the lines 5, 5; 6, 6; and 7,1 of Fig. 4 illustrating the vertical bafile members.

Fig. 8 is an enlarged sectional view showing the mounting of one of the liquid contact members in the switch.

Referring to Figs. 1 and 2 of the drawing, l0 represents a tube of nonelectrical conducting material, such Bakelite, glass or other similar material. The ends of the tube are closed by the caps H and i2. These caps provide a dual purpose. They may be made of metal enabling them to be used as terminals for contacting the conducting liquid and thereby form a part of the electrical circuit. The caps may also be provided With suitable base portions for mounting the tube on the upper platform indicated at I3.

One end of the platform i3 is secured by the hinge M to the intermediate platform I 5 adja- 5 cent one end of the latter. The other end of platform [5 is hinged, as at It, to one end of the base platform IT. The platforms l5 and I I are disposed beneath the top platform I 3 to provide a compact and convenient assembly. The base 10 platform may be supported on a body which may tilt or otherwise change its aXis with respect to the horizontal, thereby effecting the flow of the fluid within the switch regardless of the positions of the top and intermediate platforms. 15

The hinge connections [4 and it between the platforms may be biased by a spring tending to collapse the platforms so that one rests upon the other as illustrated in Fig. 1.

The tube it is partially filled with a conducting 20 liquid, such as mercury, as indicated at l8.

To retard arcing between the mercury and the contacts in the switch, through which the electrical circuits are energized, and to prevent oxidation within the tube which may occur even though 25 the tube has been partially exhausted it is preferable to fill the remainder of the tube with a nonconducting liquid such as brombenzene as illustrated at l9, Which being of lighter specific gravity will at all times float on top of the mercury. 30

The metallic caps H and 12 seal the ends of the tube, thereby maintaining the liquids therein. One or both of these caps may be provided with a binding post 251 for receiving the electrical conductors 2! for completing the electrical circuits 35 through the switch.

A plurality of contact members 22 are mounted in spaced relation along the top of the tube on each side of the center thereof and arranged to extend through the wall of the tube and the in- 0 sulating liquid, contacting the mercury when the tube is tilted at the proper inclination. These contact members are illustrated in detail in Fig.

8 wherein 23 represents a tubular shield of nonconductive material which is secured to the top 45 Wall of the tube by a threaded engagement and depends therein. The tubular shield is open at its lower end and the depending portion is provided with perforations to admit liquid to the contact members without splashing. An intern- 50 ally threaded bushing 24 is secured within the upper end of the tubular shield and is arranged to receive the threaded contact member 22 which may be adjusted to any desired position by turning the same. A packing 25 which is ar- 55 ranged to be compressed by the gland member .26 is provided for sealing the threaded contact member in the bushing. The outer end of the contact member is provided with a binding post 2'! for attaching an electrical conductor thereto.

28 represents a hollow chamber mounted on the center of the tube and provided with a port 29 connecting the chamber with the interior of the tube. This chamber acts as a pressure chamber to allow for the expansion and contraction of the liquids under variations in temperature. This chamber also aids the flow of the liquids from one end of the tube to the other when it is tilted.

The metallic bafile members in the tube, which are illustrated in Figs. 3 to 7 inclusive, are connected to one another and at all times in contact with the mercury. They also provide a low resistance path for the flow of electric current. The longitudinal baffle member 30 is made of good electrical conducting material and is chemically inert with the liquids employed in the tube. This baffle member is preferably made of a flat strip the width of which is substantially that of the inside diameter of the tube ID and extends practically the full length thereof. One end of this strip is secured to the cap 12 as shown at 35.

The vertically disposed baiile members 32 are formed to fit the container of the inside wall of the tube and are secured to the strip 30 in spaced intervals separating adjacent contact members 23. Thus each contact member is enclosed in a separate compartment formed by the wall of the tube and the bailie members.

The bafiles and the strip forming each compartment are perforated to permit the fluid to travel therethrough when the tube is tilted. The perforations or orifices become progressively larger the Walls of the bafiie members forming the compartments toward the center of the tube, thereby permitting unrestricted flow of the liquid at the center of the tube but retarding the flow adjacent the ends of the tube. This graduated arrangement of the orifices prevents surging or splashing of the liquid which may result in the momentary completion of a circuit not intended to be energized when the tube is suddenly tilted.

The centrally disposed ports 33 in the vertical baffle members 32 are covered by the flap valves 3d arranged to open toward the center of the tube and permit the liquid to freely flow in that direction but retard the flow towards the ends of the tube. Each of these valves have a small orifice therethrough to aid in the flow of the liquid and the operation of the valve. This arrangement prevents the mercury from collecting momentarily at one end of the tube if it has been tilted quickly and thereby avoids improper operation of the circuits controlled. Thus slight bumps or disturbances Will not result in incorrect operations.

The top platform !3 and the intermediate platform l5 may be tilted by any suitable servomotor means, such as the solenoids 35 disclosed on the drawing which are provided with cores 36 arranged to be moved at different positions within the solenoids, in response to the occurrence of different conditions to which the switch is employed, for operating 7 the movable platform through the link connections 35.

This switch has many applications aside from that of aircraft flight control. It may be employed to energize control circuits in conditioned air installations where it is desirable to operate such control circuits under different humidity or temperature differentials between the interior and exterior of a building or in conjunction with the operation of industrial furnaces wherein the control circuits must be actuated from the conditions created by a plurality of pressures or temperatures. In such installations the servomotors may be thermostatic 0r pneumatic, as the installation requires.

The non-conducting liquid together with the mercury should fill the tube ll Upon tilting the tube both of these liquids seek new positions therein producing different surface levels permitting the mercury to energize different circuits through the contact members in accordance with the degree of tilting. During the shifting of the liquids the one of lighter specific gravity must be displaced by the mercury. This action retards the flow of the mercury and prevents splashing thereof against the contact members. The flow of the liquids is further retarded by reason of the restricted orifices in the baffle members, thereby providing a time delay in the operation of the circuits.

Assuming that the tube It is tilted as indicated in Fig. 2 and the mercury is in contact with two of the electrodes 22 adjacent the right end of the tube, the electrical circuits connected to these electrodes would then be closed, whereas the electrical circuits connected to the electrodes on the other or left end of the tube would be open. If the solenoid 35 was suddenly deenergized the left end will drop and the tube would then assume the inclination of the platform I?) producing a tilt of the tube in the opposite direction of substantially the same degree as that shown. In readjusting its surface level the mercury will flow to the left but stay in the lower part of the tube. The majority of the mercury being in the right end of the tube before it tilts, creates a force it flows to the center of the tube because it increases in speed OWing to the momentum gained in flowing and by reason of the fact that the orifices in the bafiie members become larger toward the center of the tube and the fiap valves 3d open in that direction. This action creates a low pressure in the right end or high part of the tube and higher pressure in the left end of the tube which aids the flow of the nonconducting liquid in the opposite direction along the upper part of the tube. As the mercury continues to flow from the center of the tube toward the left end the orifices become smaller and the valves 3 are closed against the movement thereof. The movement of the mercury is thus retarded, which prevents it from splashing against the electrodes or being carried beyond the level it finally assumes, which would create premature or false closing of the electrical circuit. Thus the baiiiing arrangement together with the graduated orifices and the nonconducting liquid produces a smooth adjustment of the surface of the mercury when the tube is tilted from one position to another.

I claim: V

1. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having currentcarrying properties, an electrode arranged to be connected to one part of a circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor eX- tending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, and ports spaced along the conductor for the travel of liquid therethrough, said ports diminishing in capacity toward the ends of the tube.

2. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of a circuit and exposed exteriorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor extending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, said conductor being provided with ports spaced along the same, and vertical bafiies spaced along the conductor to retard the longitudinal flow of the liquid when the tube is tilted, said baflies having perimetral surfaces filling the inner wall of the tube.

3. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of a circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor extending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, said conductor being provided with ports spaced along the same, and vertical baiiles spaced along the conductor to retard the longitudinal flow of the liquid when the tube is tilted, said baffles being provided with ports for the travel of liquid therethrough.

i. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of a circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor extending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, vertical baiiies spaced along the conductor to retard the longitudinal flow of the liquid when the tube is tilted, ports in said bafiles through which the liquid may travel, and means whereby the travel of the liquid in one direction through said ports is restricted.

5. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of a circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor extending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, vertical bafiles spaced along the conductor to retard the longitudinal flow of liquid when the tube is tilted, parts in said baiiies, and valvular means per1nitting the flow of liquid through said ports in one direction while restricting the flow in the other direction.

6. In an electric switch, the the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of a circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, a second electrode comprising a metallic conductor ext-ending longitudinally of the tube and in contact with the liquid; said conductor being arranged to be connected to another part of the circuit, vertical bafiies spaced along the conductor to retard the longitudial flow of liquid when the tube is tilted. ports in said bailies, said ports diminishing in ca pacity toward the ends of the tube, and valvular means for restricting the capacity of said ports for the flow of the liquid toward the ends of the tube while permitting unrestricted flow toward the center of the tube when the tube is tilted.

7. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, a plurality of electrodes arranged to be connected to different circuits and exposed in spaced relation within the tube, the liquid being out of contact with certain of the electrodes when the tube is substantially horizontal but coming necessarily into electrical contact with the electrodes when the tube is given the proper inclination, means for electrically connecting said circuits to the liquid, and perforated shields of nonconductive material surrounding the portions of the electrodes within the tube.

8. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of the circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, and an expansion chamber communicating through a retricted port with the tube to permit the safe expansion of the liquid due to temperature variations.

9. In an electric switch, the combination of a tube of nonconductive material and arranged to contain a liquid having current-carrying properties, an electrode arranged to be connected to one part of the circuit and exposed interiorly of the tube, the liquid being out of contact with the electrode while the tube is substantially horizontal, but making contact therewith when the tube is given the necessary inclination, and an air chamber superimposed in and communicating through a restricted port with the tube to permit the safe expansion of the liquid due to temperature variations.

JAMES M. HENDRICKSON. 

